Field
Exemplary embodiments of the present invention relate in general to the field of an illumination apparatus using semiconductor light emitting diodes (LEDs) as a light source, and more specifically to an illumination apparatus using semiconductor LEDs that can enable all LEDs to emit light in consideration of fluctuations in the magnitude of an alternating current (AC) voltage when a plurality of LEDs are driven using the AC voltage.
Discussion of the Background
In recent years, a semiconductor light emitting diode (LED) has been utilized as a light source in many fields due to its various characteristics, such as high efficiency, low power, and high luminance. In particular, the use of illumination systems adopting semiconductor LEDs instead of conventional incandescent light bulbs or fluorescent lamps in the field of illumination has rapidly increased in recent times.
Since conventional illumination apparatuses using incandescent light bulbs or fluorescent lamps as light sources emit light using commercially available alternating current (AC) voltage, semiconductor LEDs for illumination also should be capable of being driven using an AC voltage.
Typically, to drive semiconductor LEDs using an AC voltage, a circuit may be configured to convert an AC voltage having positive and negative values into a rectifying current voltage having a positive value, and to adjust the number of emitting semiconductor LEDs with fluctuations in the magnitude of the rectifying current voltage.
In the above-described typical technique, with fluctuations in the magnitude of the rectifying current voltage, some of the plurality of semiconductor LEDs may continuously emit light over an extended light emitting time, while some of the remaining semiconductor LEDs emit light only when the magnitude of the rectifying current voltage is equal to or higher than a specific value. Thus, semiconductor LEDs constituting an illumination apparatus may have different light emitting times. As a result, some of the semiconductor LEDs constituting the illumination apparatus may wear out earlier than the others, thereby deteriorating a light emitting state of the illumination apparatus and even preventing operation of the illumination apparatus.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form any part of the prior art nor what the prior art may suggest to a person of ordinary skill in the art.